Rising fuel and input costs are having a significant impact on the profitability of the fishing sector and increasing the need for vessels to improve operational efficiency. In particular, smaller vessels that do not have the economies of scale must maximize input-output efficiency to remain viable. There is also the consideration that improved fuel efficiency in fishing vessels will reduce the carbon footprint of the sector. Measuring vessel and fleet efficiency is important for these reasons, but it is also important to correctly measure efficiency to determine how best to manage a fleet and determine how ecosystem, regulatory and market changes will impact fleet viability and operability. This paper uses stochastic frontier analysis (SFA) to assess the efficiency of fishing vessels in the Irish demersal otter trawl nephrops fishery. Clear evidence of efficiency-heterogeneity across vessels in the fishery is reported, even when controlling for vessel-specific characteristics, such as vessel length, age and engine power. The drivers of efficiency are also investigated and we find that the use of vehicle monitoring systems (VMS) data allows for more spatially and temporally detailed information to improve fleet efficiency analysis.